我创建了一个链表插入程序，我想在按下1时插入节点，按下0时退出，但只插入第一个节点，即头部，而不是其他节点。。。。似乎第一个节点工作正常，但其他节点没有插入。。请帮助确定问题所在。

import java.util.*;
// A simple Java program for traversal of a linked list 
public class LinkedList { 
    Node head; // head of list which is object of Inner Node Class.. thus head.data is a valid statement..

    /* Linked list Node.  This inner class is made static so that 
       main() can access it */
    static class Node { 
        int data; 
        Node next;
        //Constructor
        Node(int d) 
        { 
            data = d; 
            next = null; 
        } // Constructor 
    } 

    /* This function prints contents of linked list starting from head */
    public void printList() 
    { 
        Node n = head; 
        while (n != null) { 
            System.out.print(n.data + " "); 
            n = n.next; 
        } 
    } 

    /* method to create a simple linked list with 3 nodes*/
    public static void main(String[] args) 
    { 
        Scanner sc=new Scanner(System.in);

        int dt=0;
        /* Start with the empty list. */
        LinkedList llist = new LinkedList(); 

        System.out.println("Enter 1 for entry 0 for exit");
        int p = sc.nextInt();
        while(p!=0)
        {
            if(llist.head==null)
            {
                System.out.println("Enter the first data in linked list");
                dt=sc.nextInt();
                llist.head = new Node(dt);
                llist.head.next=null;
            }
          else     //problem is here// 
            {  Node n=llist.head.next;
                 System.out.println("Enter the data in linked list");
                 dt=sc.nextInt();  
                while (n != null)
                { 
                    Node nd = new Node(dt); 
                    nd.next = null;
                }
            }
        System.out.println("Enter 1 for entry 0 for exit");    
        p = sc.nextInt();    
        }

        llist.printList(); 
    } 
}